Aluminum alloy as bearing metal



Patented Sept. 17,1940

UNITED STATES,

ALUMINUM ALLOY AS BEARING METAL Eugen Vader's, Frankfort-on-the-Main, Germany, assignor to Yerelnigte Deutsche Metallwerke Aktiengesellschaft,

Frankfort on the Main- Heddernheim, Germany I -No Drawing. Original application December 15,

1937, Serial No. 180,029. Divided and this application December 26, 1939, Serial No. 311,057. In Germany December 16, 1936 4 Claims. (01. 75-148 In the white metal bearings heretofore commonly used the base metal consists principally of tin or of lead. The tin generally contains additions of antimony, bismuth, copper, etc., where- 3 as the lead is alloyed principally with antimony and bismuth. The bearing metals having a tin base have up to now been considered the best of their kind. But in consequence of their high tin content which amounts up to 90%, they are very expensive so that for the sake of economy the expensive tin has been replaced by the cheaper lead. The lead content is very often used in the same proportion as the tin in the tin bearing metals. Even the additions are very often the 3 51 same.

Since, according to views very often held, such metal alloys are best suited for hearing purposes in which the structure is composed of various hard components, it should be theoretically pos- 2 sible to use every metal as base metal for a bearmg metal alloy, provided that other metals exist, which when added to this base metal alloy, cform; hard compounds with it. Aluminum is known to form numerous compounds with other metals and it has been proposed to use alumi-.-

num alloys for hearing purposes. This has, on several occasions, been tried but with very little success considering the fact that most aluminum bearing metals of the type referred to contain hard compounds which wear the axle too much:

Bearing metals of this kind are, e. g., the aluminum silicon-alloys with high silicon content or aluminum-magnesium-silicon-alloys.

According to the present invention much more useful aluminum alloys result from the addition of metalswhich form with the aluminum none or at least only few hard compounds, thus resulting in no damage being done to the axle even after an extended time of working. Such additions o are antimony and lead which may be present in quantities up to each. The antimony forms with aluminum the compound AlSb which is present in the base alloys as hearing component. Lead-does not combine with! aluminum. Ac- 5 cording to the opinion of several experts it is not solubleat all in the aluminum. If aluminum be melted together with lead, at the time of solidiflcation a separation of the aluminum and lead takes place i. e. the lead is as insoluble in the 5 aluminum as oil in water. By adding antimony to the aluminum this sharp separation of lead from the aluminum is obviated, so that with the presence of a sufficient quantity of antimony larger quantities of lead are distributed in the 55 aluminum, resulting in an alloy which shows a structure more especially suitable for bearing purposes. Apart from aluminum' an AlSb compound is' contained in it, while lead is either alloyed with this Al-Sb compound, or else is segregated in form of small drops which form an im- 5 Thus they are easily formable even ina cold state.

vThe sliding properties have been ascertained with an especially suitably alloy consisting of 2.5% Pb, 2.5% Sb and the balance aluminum by a bearing testing installation. On that occasion 2o specific surface pressures of aliout 200 kg./cm. could be reached at a speed of 10 m./sec., whereby the bearing temperature rose up to-100 C. The test axle that consisted of non-hardened steel was perfectly-smooth and free from indents at the end of the test. Apart from the bearing testing machine, tests were made in combustion motors in which the connecting rod bearings consisted of the new aluminum alloys. These combustion motors have been driven by an electrical motor, so that the hearings were fully charged. Also in that case the bearings of the new alloy proved successful, for during a working period of about 6 weeks the motors did not show any defects.

On further investigation of these alloys it 'was shown that the lead and the antimony can be replaced in ,part at least by one of the metals of the group tin, cadmium, calcium and arsenic in quantities of 0.1-5%. Thus it is possible to make 40 use with equal success of an alloy of the following composition:

,lE'ercent In cases in which the price of the bearing metal is of lesser importance, the tin content may also be higher. An alloy having a higher tin content is about the following: I

v Percent Pb,' 2.5 Sb. 2.3 Sn g Al Balance Since tin alloys well either with antimony or with erties.

lead, it is particularly valuable as addition to the ternary aluminum-lead-antimony-alloy, but also the other metals added to this three-part-alloy result in very useful-bearing metals.

' While the additionalmetals mentioned above influence chiefly the sliding properties, the further possible. additions of at least one of the metals of the group consisting of copper, nickel, cobalt, ir'on, manganese and zinc in quantities of 0.1-10% and silicon in quantities of 0.1-3% especially efi'ect a strengthening of the bearing metal which consequently is more suitable'to resist higher pressures. Especially an addition of manganese has proved very effective, inasmuch as it not only increases the hardness of the alloy, but even improves essentiallyv the sliding prop- An alloy that provedparticularly useful for the automobile motor is composed as follows:

2.5% Pb, 2.5% Sb, 3% Mn, remainder Al.

Further alloys that correspond about with the properties of the above mentioned alloys are as 7 follows: a

a The addition of metals of a higher melting point 1 'peratures.

further serve-the purpose of making the bearing metals capable of resisting higher temperatures. While it is correct that-With most of the additional metals named above the melting point of aluminum is lowered to the eutectic point, the presence of these metals having higher melting points, more especially if lead and tinwith their lower melting point are present, result in the direction of a better resistance to higher'tem- Bearing temperatures of up-to 120 0: could be reached without a clinging or sticking to the axle having occurred. Naturally with such high temperatures the higher'heat expansion of the aluminum alloys has to be taken into account. by the provision of a greater bearingplay.

If the new bearing metals are used under fa vorable conditions, i. -e., presenceof ample quantitles of lubricants, they show but a small wear, even after a comparatively-short running-in period.

- Summing up it may be said that with the new bearing metals having an aluminum base as compared with the hitherto lmown bearing metals, the following advantages existi 1. Easier running-in,

2. High resistance to wear,

3. Possibility to use .unhardened axles, 4. High resistance to temperature.

The alloys may be used in-accordance with the invention for any'casting method, as sand casting, chill casting, pressure die casting and cerrtrifugal casting. With centrifugal casting the temperatures and numbers of revolutions must be adjusted in such away that-the segregations remain at a minimum. The alloys may further be pressed, forged or rolled. In this respect it is surprising that the annealing in the drawingof rods and tubes may be accomplished at about 500 C. in spite of the lead and antimony contentwithout a segregation of the alloys occurring thereby.-

possible, first of all antimony is melted together with aluminum whereupon lead is added as such or as a preliminary'all'oy.

The rolling possibility moreover makes it possibleto roll up the alloys'to a firmer sheet base that may consist of iron or copper alloys or also of hardenable aluminum alloys and to produce from the compound metal sheets thusobtained' especially firm bearing shells.

This application is a division of my copending application, Serial No. 180,029, filed December 15, 1937,:now Patent No. 2,196,236, patented April 9, .1940.

I. claim:

1. A bearing metal alloy containing about 1- 10% of lead, 1-10% of antimony, 0.1-3% of sili-' con, and 01-10% of a metal of the group consisting of nickel, cobalt and iron, the balance being substantially all aluminum.

2. A'bearing metal alloy containing about 1- 10% of lead, 1-10% of antimony, 0.1 3% of silicon, and 01-10% of nickel, the balance being substantially all aluminum.

3. A bearing metal alloy containing about 1- 10% of lead, 1-10% of antimony, 0.13% of silicon 'and- 01-10% of cobalt, the balance being substantially all aluminum.

4. A bearing metal alloy containing about 1- 10% of lead, 1-10% of antimo'ny, 0.1-3% of silicon, and 0. 1-10% of iron, the balance being substantially all aluminum.

-' EUGEN VADERS.

For the produ'ction'of an alloy as uniform as 

